diff --git a/instrumentation/logback/logback-mdc-1.0/library/src/main/java/io/opentelemetry/instrumentation/logback/mdc/v1_0/OpenTelemetryAppender.java b/instrumentation/logback/logback-mdc-1.0/library/src/main/java/io/opentelemetry/instrumentation/logback/mdc/v1_0/OpenTelemetryAppender.java
index 4b3a3a3bcbee..f3c148b9647c 100644
--- a/instrumentation/logback/logback-mdc-1.0/library/src/main/java/io/opentelemetry/instrumentation/logback/mdc/v1_0/OpenTelemetryAppender.java
+++ b/instrumentation/logback/logback-mdc-1.0/library/src/main/java/io/opentelemetry/instrumentation/logback/mdc/v1_0/OpenTelemetryAppender.java
@@ -11,6 +11,7 @@
 
 import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.classic.spi.LoggerContextVO;
+import ch.qos.logback.classic.spi.LoggingEventVO;
 import ch.qos.logback.core.Appender;
 import ch.qos.logback.core.UnsynchronizedAppenderBase;
 import ch.qos.logback.core.spi.AppenderAttachable;
@@ -82,22 +83,27 @@ public ILoggingEvent wrapEvent(ILoggingEvent event) {
             ? new LoggerContextVO(oldVo.getName(), eventContextMap, oldVo.getBirthTime())
             : null;
 
-    return (ILoggingEvent)
-        Proxy.newProxyInstance(
-            ILoggingEvent.class.getClassLoader(),
-            new Class<?>[] {ILoggingEvent.class},
-            (proxy, method, args) -> {
-              if ("getMDCPropertyMap".equals(method.getName())) {
-                return eventContextMap;
-              } else if ("getLoggerContextVO".equals(method.getName())) {
-                return vo;
-              }
-              try {
-                return method.invoke(event, args);
-              } catch (InvocationTargetException exception) {
-                throw exception.getCause();
-              }
-            });
+    ILoggingEvent wrappedEvent =
+        (ILoggingEvent)
+            Proxy.newProxyInstance(
+                ILoggingEvent.class.getClassLoader(),
+                new Class<?>[] {ILoggingEvent.class},
+                (proxy, method, args) -> {
+                  if ("getMDCPropertyMap".equals(method.getName())) {
+                    return eventContextMap;
+                  } else if ("getLoggerContextVO".equals(method.getName())) {
+                    return vo;
+                  }
+                  try {
+                    return method.invoke(event, args);
+                  } catch (InvocationTargetException exception) {
+                    throw exception.getCause();
+                  }
+                });
+    // https://github.com/qos-ch/logback/blob/9e833ec858953a2296afdc3292f8542fc08f2a45/logback-classic/src/main/java/ch/qos/logback/classic/net/LoggingEventPreSerializationTransformer.java#L29
+    // LoggingEventPreSerializationTransformer accepts only subclasses of LoggingEvent and
+    // LoggingEventVO, here we transform our wrapped event into a LoggingEventVO
+    return LoggingEventVO.build(wrappedEvent);
   }
 
   @Override
diff --git a/instrumentation/logback/logback-mdc-1.0/library/src/main/java/io/opentelemetry/instrumentation/logback/mdc/v1_0/internal/UnionMap.java b/instrumentation/logback/logback-mdc-1.0/library/src/main/java/io/opentelemetry/instrumentation/logback/mdc/v1_0/internal/UnionMap.java
index 5da8c72b1a46..e84b136d7d0d 100644
--- a/instrumentation/logback/logback-mdc-1.0/library/src/main/java/io/opentelemetry/instrumentation/logback/mdc/v1_0/internal/UnionMap.java
+++ b/instrumentation/logback/logback-mdc-1.0/library/src/main/java/io/opentelemetry/instrumentation/logback/mdc/v1_0/internal/UnionMap.java
@@ -5,10 +5,12 @@
 
 package io.opentelemetry.instrumentation.logback.mdc.v1_0.internal;
 
+import java.io.Serializable;
 import java.util.AbstractMap;
 import java.util.AbstractSet;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.Map;
@@ -21,7 +23,8 @@
  * <p>This class is internal and is hence not for public use. Its APIs are unstable and can change
  * at any time.
  */
-public final class UnionMap<K, V> extends AbstractMap<K, V> {
+public final class UnionMap<K, V> extends AbstractMap<K, V> implements Serializable {
+  private static final long serialVersionUID = 1L;
 
   private final Map<K, V> first;
   private final Map<K, V> second;
@@ -128,6 +131,11 @@ public Set<Entry<K, V>> entrySet() {
         Collections.unmodifiableSet(new ConcatenatedSet<>(first.entrySet(), filteredSecond));
   }
 
+  private Object writeReplace() {
+    // serialize this object as HashMap
+    return new HashMap<>(this);
+  }
+
   // Member sets must be deduped by caller.
   static final class ConcatenatedSet<T> extends AbstractSet<T> {